1. Technical Field
Several aspects of the present invention relates to a coil unit suitable for contactless power transmission and an electronic apparatus or the like using the coil unit.
2. Related Art
There is known contactless power transmission that uses electromagnetic induction to transmit power without using a metal contact. As applications of contactless power transmission, charging of a cell phone, charging of a home appliance (e.g., a handset), and the like have been proposed.
In recent years, cell phones are required to be downsized further. For this reason, a coil unit for transmitting power must also be further downsized, particularly, in the thickness dimension. For the purpose of providing a battery pack interface whose use allows charging a cell phone including a battery pack by only placing the cell phone on a power transmission apparatus, JP-A-2006-311712 discloses a technology for transmitting power to a cell phone (1) including a battery pack (3) storing a protection circuit (5) and a secondary battery (4) and a charging control circuit (6) via contact terminals (9) and (10) using a battery pack lid (2) including a power transmission interface (8) and a rectifier circuit (7).
In JP-A-2006-311712, a coil serving as the power transmission interface (8) is included in the battery pack lid (2) together with the rectifier circuit (7). The inclusion of the rectifier circuit (7) makes the battery pack lid (2) thicker. Also, the battery pack lid (2) is available only as a battery pack; therefore, its use condition, that is, its flexibility in usage is significantly restricted.